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- 저자 : Shaya, D. (검색결과 8 건)
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Composite active site of chondroitin lyase ABC accepting both epimers of uronic acid
Shaya, D.,Hahn, Bum-Soo,Bjerkan, Tonje Marita,Kim, Wan Seok,Park, Nam Young,Sim, Joon-Soo,Kim, Yeong-Shik,Cygler, M. Oxford University Press 2008 Glycobiology Vol.18 No.3
<P>Enzymes have evolved as catalysts with high degrees of stereospecificity. When both enantiomers are biologically important, enzymes with two different folds usually catalyze reactions with the individual enantiomers. In rare cases a single enzyme can process both enantiomers efficiently, but no molecular basis for such catalysis has been established. The family of bacterial chondroitin lyases ABC comprises such enzymes. They can degrade both chondroitin sulfate (CS) and dermatan sulfate (DS) glycosaminoglycans at the nonreducing end of either glucuronic acid (CS) or its epimer iduronic acid (DS) by a beta-elimination mechanism, which commences with the removal of the C-5 proton from the uronic acid. Two other structural folds evolved to perform these reactions in an epimer-specific fashion: (alpha/alpha)(5) for CS (chondroitin lyases AC) and beta-helix for DS (chondroitin lyases B); their catalytic mechanisms have been established at the molecular level. The structure of chondroitinase ABC from Proteus vulgaris showed surprising similarity to chondroitinase AC, including the presence of a Tyr-His-Glu-Arg catalytic tetrad, which provided a possible mechanism for CS degradation but not for DS degradation. We determined the structure of a distantly related Bacteroides thetaiotaomicron chondroitinase ABC to identify additional structurally conserved residues potentially involved in catalysis. We found a conserved cluster located approximately 12 A from the catalytic tetrad. We demonstrate that a histidine in this cluster is essential for catalysis of DS but not CS. The enzyme utilizes a single substrate-binding site while having two partially overlapping active sites catalyzing the respective reactions. The spatial separation of the two sets of residues suggests a substrate-induced conformational change that brings all catalytically essential residues close together.</P>
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Shuxia Li,Yunru An,Shaya Hailati,Jing Zhang,Yuman Cao,Yushi Liu,Jincai Geng,Tianming Hu,Peizhi Yang 한국식물학회 2019 Journal of Plant Biology Vol.62 No.5
Cytokinin oxidase/dehydrogenase (CKXs) areinvolved in various physiological processes, includingcytokinins (CKs) catabolism, root system architecture andresponse to abiotic stresses in plants. Alfalfa (Medicagosativa) is a widely cultivated forage which is frequentlythreatened by high salinity, and the potential role of CKXs inalleviating the salt stress in alfalfa lacked attention. In thisstudy, we isolated a CKX gene from alfalfa, MsCKX(MK177192), and identified its biological functions byoverexpressing it in Arabidopsis. MsCKX shares high sequenceidentity with CKX from other legume plants, especiallyMedicago truncatula (98%). MsCKX was clearly tissuespecific,and it was mainly expressed in roots. In addition,the expression of MsCKX increased under salt stress andabscisic acid (ABA) treatment. Overexpression of MsCKXgene increased the activity of CKX, which led to an enlargedroot system in transgenic Arabidopsis plants. Overexpressionof MsCKX gene enhanced salt tolerance of transgenic plantsby maintaining a higher K+/Na+ ratio, enhancing the activities ofantioxidant enzymes to scavenge ROS and increasing theexpression levels of stress-related genes (P5CS1, DREB2,ion transporters and H+ pumps). Taken together, these resultsshed light on the roles of MsCKX involved in salt toleranceand may have applications in salt-resistant breeding ofalfalfa.
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Mohtavinejad, Naser,Dolatshahi, Shaya,Amanlou, Massoud,Ardestani, Mehdi Shafiee,Asadi, Mehdi,Pormohammad, Ali Techno-Press 2021 Advances in nano research Vol.10 No.5
Infection is one of the major mortality causes throughout the globe. Nuclear medicine plays an important role in diagnosis of deep infections such as osteomyelitis, arthritis infection, heart valve and heart prosthesis infections. Techniques such as labeled leukocytes are sensitive and selective for tracking the inflammations but they are not suitable for differentiating infection from inflammation. Anionic linear-globular dendrimer-G<sub>2</sub> was synthesized then conjugation to gemifloxacin antibiotic. The structures were identified by FT-IR, <sup>1</sup>H-NMR, C-NMR, LC-MS and DLS. The toxicity of gemifloxacin and dendrimer-gemifloxacin complex was compared by MTT test. Dendrimer-G<sub>2</sub>-gemifloxacin was labeled by Technetium-99m and its in-vitro stability and radiochemical purity were investigated. In-vivo biodistribution and SPECT imaging were studied in a rabbit model. Identify and verify the structure of the each object was confirmed by FT-IR, <sup>1</sup>H-NMR, C-NMR and LC-MS, also, the size and charge of this compound were 128 nm and -3/68 mv respectively. MTT test showed less toxicity of the dendrimer-G<sub>2</sub>-gemifloxacin than free gemifluxacin (P < 0.001). Radiochemical yield was > %98. Human serum stability was 84% up to 24 h. Biodistribution study at 50 min, 24 and 48 h showed that the complex is significantly absorbed by the intestine and accumulation in the lungs and affects them, finally excreted through the kidneys, biodistribution results are consistent with results from full image means of SPECT/CT technique.
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Mahdis Mohammadpour,Neema Bakhshalian,Shahriar Shahab,Shaya Sadeghi,Soodeh Sarikhani 대한영상치의학회 2014 Imaging Science in Dentistry Vol.44 No.2
Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.
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Mohammadpour, Mahdis,Bakhshalian, Neema,Shahab, Shahriar,Sadeghi, Shaya,Ataee, Mona,Sarikhani, Soodeh Korean Academy of Oral and Maxillofacial Radiology 2014 Imaging Science in Dentistry Vol.44 No.2
Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.
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Co‑simulation Improvement for Uncertain Flexible Robot Arm
Lilia Zouari,Mossaad Ben Ayed,Slim Chtourou,Shaya Abdullah Alshaya,Mohamed Abid 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
Flexible robot arm driven by Brushless DC Motor (BDCM) under uncertainties represents one of the most complex and heterogeneous system. Indeed, the verifcation phase becomes a great challenge for designers. Avoid and predict risks accurately at earlier stage represents the main purpose of the Computer-Aided Design (CAD) feld. This paper treats the case of robotics system for tracking trajectory problem and attempts to improve the verifcation phase by identifying the most suitable co-simulation technique. For the system analyzed in this paper, the fexible robot arm driven by Brushless DC actuator is verifed using the Model In the Loop (MIL) technique, the Software In the Loop (SIL) technique and CODIS+technique. Each one verifes the system according to a particular abstraction level. The performance of each technique is determined by measuring the accuracy and time simulation. Experimental results have revealed that CODIS+is the most adequate technique for fexible robot arm, outperforming MIL and SIL by 4–5 times.
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Smart Recognition COVID-19 System to Predict Suspicious Persons Based on Face Features
Ben Ayed Mossaad,Massaoudi Ayman,Alshaya Shaya A. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3
The coronavirus (COVID-19) is identifi ed at fi rst in Wuhan in December 2019. The apparition of the COVID-19 virus is widely spread to concern all countries worldwide. The World Health Organization (WHO) on March 11 declare COVID-19 a pandemic. This Virus causes a serious infection of the respiratory system. Its high transmission constitutes great problems and challenges. The WHO proposes many actions to limit the spread of the virus such as quarantine and decrease or halt fl ights between states. The actions taken by states in airports are to detect suspicious persons with COVID-19. We aimed to provide a Computer-Aided Diagnosis (CAD) framework to predict suspicious COVID-19 person. This prediction identifi es suspicious persons who suff er from shortness breath which is the main symptom of this disease. Extract shortness breath anomaly through the estimated heart rate from face based-video is the main contribution of the present paper. We developed a Smart Recognition COVID-19 (SRC) system to estimate the breath score. In conclusion, our study achieves an accurate breath score. The error is about 1 breath per minute. The proposed solution is of great importance because it helps managers in the airport to predict suspicious COVID-19 passengers.
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